Up to the present time, certain wraparound packages have customarily consisted of a cardboard blank. The articles are visible only at the ends of the package, so that the carton must be printed upon in order to make the contents of the package known, since these packages customarily are packages for sale. In contrast, so-called shrink packages, which consist entirely of transparent shrink film, permit the contents of the package to be recognized; moreover, these shrink packages are cheaper than the above-mentioned packages made of cardboard. However, these shrink packages can be produced and closed only with relatively high expense for machinery and labor.
It is known to place the articles to be wrapped on a tray made of cardboard, corrugated board, or the like, in order to give the group of articles a better unity before the shrink film is applied, and to prevent the articles from falling apart after the shrink film has been torn off by the user. These packages require relatively lrge expense at the point of packaging, for a machine for setting up the tray, means for heat-sealing, cutting-off, and applying the shrink film, and a heating tunnel for the shrinking procedure are required.
It is also known to insert individual articles or several articles into a pre-fabricated, mechanically-stretched plastic film casing; when the streching tool is removed, the film embraces tightly the group of objects. A heating tunnel for a shrinking procedure is not necessary; here too, however, the expense for mechanical devices is relatively great, while the operating speed is low because of the discontinuous packaging operation.
It is common to all the above-mentioned types of packages that they are based either on paperboard as the packing material or on plastic film as the packing material, and therefore price fluctuations of the given packing material affect the price of the package produced, a change to other packaging materials not being possible without extensive mechanical alterations.
Therefore, it is the object of the invention to develop a package of the initially-mentioned type in such a manner that expense for machinery and labor is small at the point of packaging; that the package permits its contents to be easily recognized; and that, without alteration of the mechanical equipment at the point of packaging, an optimal selection of material is possible according to the price fluctuations of the materials employed.
According to the invention, this object is accomplished in that the blank is provided, at its two closure margins, with a closure strip consisting of paperboard, and that the intermediate area of the blank consist at least partially of a film of plastic material, which is joined to the paperboard closure strips.
The surface areas of the package which consist of film can be selected to vary in size and permit the contents of the package to be well recognized. For example, the blanks can be produced in large quantities, and therefore cost-favorably, in a central production plant on high-output equipment. They can be delivered, for example, individually or in the form of long, rolled-up strips which can be separated into individual blanks on tear lines as the latter are placed about the groups of articles. Alternatively, a composite web may be supplied, from which the blanks can be punched out as the first step in the packaging operation. Thus, the two materials, paperboard and film, do not have to be processed individually and successively at the point of packaging; rather, the completed blank is wrapped around the articles and secured. This permits very high operation speeds with great reliability because of the mechanical closure. Expense for machinery and labor at the point of packaging is therefore small, so that the package according to the invention can be used economically even in the case of small quantities of packages. Cost increases of paperboard can be compensated by selecting the proportion of paperboard to be relatively small and by limiting it to the two closure strips, for example. On the portions of the package consisting of paperboard, apertures, tear strips, mechanical locking means, and the like may be provided in the manufacture of the blanks with small expense for labor, which hitherto was not possible, or was possible only with great expense, in the case of conventional film packages.
Preferably, the plastic film used in encasing the groups of articles to be wrapped is an elastically-stretchable film. The time-consuming operations of heat-sealing and shrinking plastic film are eliminated, as the blank can be mechanically closed by means of the paperboard closure strips. The force with which the film is tightened about the articles is not supplied in a heating tunnel with high energy requirements, but rather mechanically, by stretching of the film; the energy requirement is substantially smaller; the operating speed can be greatly increased, because the procedure is a matter of a simple mechanical tensioning which can be performed rapidly. As an alternative, however, shrink film can be employed.
One embodiment of the invention concept provides that the plastic film be joined, at its edges, with an edge of the closure strips and, if desired, with an upper paperboard cover strip. This permits a relatively small proportion of film to be used. As an alternative, however, the plastic film may extend over the entire area of the blank and the closure strips and, if desired, the upper paperboard cover strip may be attached thereto by means of adhesive or by lamination.
In this way, the film imparts additional strength to the paperboard strips, so that a relatively thin and therefore inexpensive quality of paperboard can be employed.
Further advantageous embodiments of the concept of the invention are the subject matter of dependent claims.
The invention is explained below in more detail with reference to embodiments represented in the drawings.